I think this phenomenon is the result of a confirmation bias. Half of all people are below average intelligence, so if you live in a majority democrat region most of the stupid people are going to be democrats the same for majority republican regions. Add to that the social friction with going against the herd, the friction must be worthwhile to the person so it is more likely a lot of thought went into someone's conclusions if they're willing to make their life more difficult for it, ideological minorities like that are (probably not remotely near astronomically) more likely to be a more thoughtful. Both of these pressures skew the majority political leaning in any region below average intelligence and have the opposite effect on the minority.

This might be the most reasonable explanation. In the end, the republicans I talked to were very reluctant to hint they vote republican, so in general they would approach issues much more carefully. It still doesn't fully explain the democrat behavior.

I definitely know more democrats than republicans (my area votes 80% democrat). But they are highly educated people (think U Chicago, Georgia Tech etc.) still believing every opinion their favorite news outlet sells them. I find that disturbing. Not the fact that they believe most of the party lines, but believing and defending ALL of them, like the party can do no wrong.

My experience is also the opposite fwiw. To be fair, I don't think I know any democrats who actually like the party. They're more "not republican" than democrat. Maybe the democrats you've talked to are the true believers. The only example I can come up with that matches your experience is my dad, so maybe it's generational?